Pneumatic distribution for twostroke internal combustion engines



w. BRESLAV JW PNEUMATIC DISTRIBUTION FOR TWO-STROKE INTERNAL COMBUSTION ENGINES Filed June 15, 1957 2 Sheets-Sheet l INVENTOR WCTOR B ESLAV n 7 v. BRIESLV PNEUMATIC DISTRIBUTION FOR TWO-STROKE INTERNAL COMBUSTION ENGINES Filed June 15, 1937 2 Sheets-Sheet 2 Inventor: 1/16 T0 BHESLAV Patented Jan. 16, 1940 amen rarer rice PNEUMATIC nis'riarsprron roa TWO- STROKE INTERNPiL GIN ES CQMBUSTION EN- Victor Breslav, Brussels, Belgium, assignor to Interna Holding, Socit Ancnyme, Luxemburg, A Grand Duchy of Luxemburg Application June 15, 1937, Serial No. 148,289

r In Belgium July 24, 1936 p 9 Claims.

My invention relates totwo-stroke internal combustion engines in which scavenging is effected according to the parallel flow method, and in which the burnt gases are exhausted through ports formed at the inner end of the engine cylinder and controlled by a sealing or shutter piston, i i

According to my invention the energy necessary for causing the quick reciprocation of the 1! sealing piston which controls the covering and theuncovering of the exhaust ports is generated solely'by the pressure of the exhaust gases, the said sealing piston having no permanent connection between it and the engine crankshaft.

The device according to my invention further secures a supply of supercharging air for the engine Without any extra consumption of driving power, whereby the intake air pressure may be One embodiment of my invention will be here inafter described with reference to the accompanying drawings, in which:

Fig. l is a sectional View of the device according to my invention as applied to a two stroke internal combustion engine;

Fig. 2 is a sectional View on line 22 of Fig. 1;

Fig. 3 is a plan view of the devicev As shown in the drawings, the cylinder 5 of a two stroke internal combustion engine has its innerend wall formed by a piston 6 mounted to slide in the said cylinder and intended, when reciprocated, to cover and to uncover the ports la and lb which communicate with the exhaust duct Acollar ii is provided at the end of the skirt It of the sealing piston, so as to constitute a furthcr piston which is adapted to slide in a cylindrical recess it formed in. the head 12 of the cylinder 5. A cylindrical chamber 63 for cooling water circulation is provided in the said cylinder head and extends axially into the cavity of the piston ii, so as to determine a hermetical space I4.

{The skirt iii of the piston 53 has extending therefrom diametrically opposed arms [5a and [51) arranged to slide between guides I6, ll, l8 and lilformed in the cylinder head l2.

In diametrically arranged holes provided in the said armsand lined with bushings 2i! and 21, there is mounted a shaft 22 the intermediate portion of which is cranked and extends through a sliding block 2% adapted to reciprocate ina slide 25 formedinthe cylinder head. i

A shaft 26 having its rotary motion derived, by any suitable means from the engine drive shaft l -i is rotatably mounted in bearings 2'1 and 28 integral with the head it. and is provided with a collar 29 formed with bosses Si] and ii which are intended to act so as to displace a tappet 32 cooperating with the sliding block 24.

A ball valve 33 is provided laterally in the head it and provides for admission of atmospheric air into the chamber 34 when the piston 6 is moved to uncover the exhaust ports la and lb.

A valve 35 formed with a stem 36 which has its outer end cooperating with the bushing 20 1s adapted-when the piston 6 arrives at the end of its stroke for covering the exhaust ports la and a lbto put the chamber i l in communication with the atmosphere throughthe channel 31, and longitudinal grooves formed in the stem 36 of the valve.

The chamber 34 is connected with the combus tion chamber 38 of the cylinder by, means of a duct 39, the flow through the latter being controlled by a first (ball) valve Ml and by a second valve Mi operated through a stem 42 adaptedwhen the piston ii arrives at the end of its stroke for covering the exhaust portsto be acted upon by a projection it of the bushing 2|.

The operation of the device is as follows:

When the shutter piston t is at its lower dead centre the axis of the crank pin 23 is positioned on a straight line coinciding with the axis of the piston li so that the latter is locked against any pressure load applied thereto throughout the duration of the compression, combustion and expansion.

At the moment at which opening of the exhaust ports has to occur the piston 6 is unlocked by a push from the cam it applied to the tappet 32 which, in moving, drives in turn the sliding block 2d through a slight amount so that movement of the parts are not stopped by the friction. At this moment the piston 6 is left alone and, under the action of the pressure from the burned gases, performs its upward stroke until the ex,- haust ports "la and lb are uncovered; the law of movement of the said piston depends merely upon the latter pressure and the velocity of upward travel of the piston is a function solely of the said exhaust pressure. The energy of the gases is applied to the piston under the form of velocity'which is in turn transmitted through the latter piston to means influenced by the movement 0! the said piston and capable of storing up the said energy and of restoring it subsequently so as to cause a return movement of the said piston. In fact, when travelling upward, the piston 8 compresses the air contained in the chamher it formed between the head of the piston 6 and the end wall of the chamber [3, the volume of the said chamber Hi being so chosen that the movement of the piston 6 is braked when the latter arrives at the upper dead centre.

During its upward travel the piston draws air into the chamber 34, said. air entering the latter chamber through a channel controlled by the ball valve 33. I

When the piston 6 has arrived to its upper dead point, the sliding block has performed a complete forward and reverse movement and has its centre again in line with the axis of the piston ii; the latter is thus locked during the period of time required for scavenging and would not begin its downward movement until the cam 3| has disengaged the sliding block 24 from its dead point position.

At this moment movement of the piston is obtained from the pressure of the air compressed in the chamber I4. As the expansion energy of the said air is greater than what is necessary for moving the piston, the velocity of such movement need be braked.

Provision is made to this effect in the chamber B l, the pressure of the air contained in the latter chamber being caused to increase from atmospherical up to a value such that the whole of the energy generated by the expansion of the air in the chamber i l be spent'at the moment the piston 5 arrives at its lower dead centre.

The braking function of the air container in the chamber its is then achieved. At this moment the projection n of the bushing 2! comes to bear upon the stem 42 of the valve 4! and the latter opens the communication between the chamber 3 8 and the combustion chamber 38. Thus, an extremely powerful stream of supercharging air is blown. into the combustion chamber, said air being admitted directly into the latter without passing through the cylinder, said admission taking place at a. moment subsequent to the completion of scavenging and under a relatively high pressure with a resulting very efiicient turbulence.

As soon as the gradually increasing compression pressure in the cylinder exceeds that developed in the chamber 3d, the ball 40 cuts ofi the communication between the cylinder and the said chamber.

The operating cycle is now completed and the pneumatic distribution assembly is again in its initial condition.

To reduce the pressure in the chamber I t down to atmospheric subsequent to each return stroke of the piston ii to its lower dead centre the device may be fitted with the valve 35.

-What I claim is: 1

1. In a two-stroke internal combustion engine,

in combination with a cylinder formed with exhaust ports in the cylinder, a head for the said. cylinder, and a sealing piston slidable in the inner end of the latter for controlling the said ports, fluid-pressure means acting directly on the piston to cause controlled movement of the piston in opposite directions, the said piston being moved under the action of burned gases to uncover the said ports, means for storing up the energy applied by the said burned gases to the said piston when the latter is displaced to uncover the said ports and means for causing the stored energy to displace the piston in the opposite direction to cover the said ports, means cooperating with the said cylinder head for locking the said piston automatically during the respective periods for which the said ports are kept open or closed, and means for periodically unlocking the said piston.

2. In a two-stroke internal combustion engine, in combination with a cylinder, a head for the said cylinder, exhaust ports in said cylinder, and a sealing piston slidable in the inner end of the said cylinder to control the said ports, fluid pressure means acting directly on the piston to cause controlled movement of the piston in opposite directions, the said piston being moved under the action of burned gases to uncover the said ports, elastical means biased by the movement of the said piston under the action of the said burned gases and acting upon the said piston to return the latter to the position in which it closes the said ports, means cooperating with the said cylinder head for locking the said piston automatically in the respective periods for which the said ports are kept open or closed, and means for periodically unlocking the said piston.

3. In a two-stroke internal combustion engine, in combination with an engine cylinder, a head for the said cylinder, exhaust ports for the burnt gases in the said cylinder and a sealing piston slidable in the inner end of the said cylinder for controlling the said ports, the said piston being moved under the action of the exhaust gases to uncover the said ports, elastical means biased by the displacement of the said piston under the action of the said gases and acting upon the said piston to return the latter to the position in which the said ports are covered, a cranked shaft pivoted to the said piston along a line perpendicular to the axis of the said piston, a transversely arranged slide in the said cylinder head, a sliding block in the said slide, a transverse opening in the said sliding block to receive the crank pin of the said cranked shaft, an abutment in the said slide for arresting the movement of the said sliding block in one direction when the axis of the said crank pin lies on the axis of the said piston and for thus locking the said piston, means for acting periodically upon the said sliding block and moving the axis of the said crank pin off and away from the axis of the said piston thus unlocking the said piston in synchronism with the movements of the engine drive shaft, and means for braking the movement of the said piston when the latter, under the action of the said elastical means, arrives at the end of its stroke for covering the said ports.

a. In a two-stroke internal combustion engine as claimed in claim 3, in which the means for acting periodically upon the said sliding block and unlocking the sealing piston consist of a shaft rotated in synchronism with the movements of the engine drive shaft, bosses on the first said shaft for acting periodically upon the said sliding block and moving the axis of the said crank pin off and away from the axis of the sealing piston, thus enabling the said cranked shaft to perform an oscillation under the effect of the movement of the said piston.

5. In a two-stroke internal combustion engine, in combination with an engine cylinder, a cylinder head for the said cylinder, ports for the exhaust of the burnt gases in the said cylinder, and a sealing piston slidable in the inner end of the said cylinder for controlling the said ports, the said piston being moved under the action of the exhaust gases for opening the said ports, elastical means biased by the movement of the said piston under the action of the exhaust gases and acting to return the said piston to its position for covering th said ports, means cooperating with the piston in the respective periods in which the said ports are uncovered or covered, means for periodically effecting the unlocking f the said piston and enabling the latter to be displaced, a bore coaxial with said engine cylinder and of greater diameter than the latter formed in the engine cylinder head, a collar formed at the outer cylinunderneath the said collar and comprised between the said piston and the saidbore, air in the said chamber to be compressed when the said piston is moved for closing the exhaust ports for the burnt gases, means for admitting air into the said chamber and means for discharging the said compressed air when the said piston is at the end of its stroke for covering the said ports.

6. In a two-stroke internal combustion engine as claimed in claim 5, wherein the means for admitting air into the annular chamber formed underneath the said collar of the sealing piston and comprised between the outer cylindrical wall of the said piston and the bore formed in the cylinder head consist in a channel provided in the latter and extending between the said annular chamber and the atmosphere, an automatic loaded intake valve in the said channel, the said channel being sealed by the outer cylindrical face of the said collar when the said piston, on its travel for closing the said ports, reaches the end of its stroke.

7. In a two-stroke internal combustion engine as claimed in claim 5, wherein the means for discharging the air compressed in the annular chamber formed underneath the collar of the sealing piston and comprised between the outer cylindrical wall of the said piston and the bore formed in the engine cylinder head consist in a first aperture provided in the said cylinder head and opening into the said annular chamber, a

second aperture opening into the engine cylinder, a duct for connecting the two said apertures, a first valve interposed in the said duct and arranged in the cylinder head near the said annular chamber, a return spring for the said valve,

cylinder, a spring for the said second valve to check the flow from the engine cylinder to the said annular chamber through the said duct.

8. In a two-stroke internal combustion engine, in combination with an engine cylinder, a head for the said cylinder, ports for the exhaust of burnt gases in the said cylinder, and a sealing piston slidable in the inner end of the said cylinder for controlling the said ports, the said piston being moved under the action of the exhaust gases for uncovering the said ports, an axial cylindrical projection in the said cylinder head, said projection extending for a certain distance inside the said sealing piston and the inner cylindrical surface of the latter having a hermetical sliding fit with the said projection, a hermetical chamber formed inside the said piston and comprised between the head of the latter and the end wall of the said projection, air in the said chamher to be compressed when the said piston is displaced under the action of the exhaust gases, a water circulation cavity formed inside the said cylindrical projection, channels in the said cylinder head for supply and discharge of water into and out of the said circulation cavity, means cooperating With the said engine cylinder head for automatically locking the said piston in its alternate positions in which the said ports are uncovered or covered respectively, means for periodically unlocking the said piston in synchronism with the movements of the engine drive shaft and enabling the said piston to reciprocate, movement of the said piston in one direction being effected under the action of the exhaust gases and in the other direction under the action of the air compressed in the said hermetical chamber, means for admitting atmospheric air to the said chamber and means for braking the movement of the said piston when the latter reaches the end of its stroke for covering the exhaust ports.

9. In a two-stroke internal combustion engine as claimed in claim 8, wherein the means for admitting atmospheric air into the hermetical chamber formed between the head of the sealing piston and the end wall of the said cylindrical projection, consist in a channel for connecting the said'chamber to the atmosphere, a valve in the said channel, a spring for the said valve, and

means operated from the movements of the said sealing piston for actuating the said valve and opening the communication between the said chamber and the atmosphere when the said'piston reaches the position in which the exhaust ports are closed.

- VICTOR BRESLAV. 

